A brief glance around the Green Bay Packers’ locker room tells Sam Barrington all he needs about how much things have changed the past 2-1/2 years.

Veteran inside linebackers A.J. Hawk, Brad Jones and Jamari Lattimore have been replaced by the likes of rookie Jake Ryan, Carl Bradford and Nate Palmer, a converted outside prospect who was a member of Barrington’s 2013 draft class.

While Clay Matthews occasionally factors into the inside equation, it’s the 24-year-old Barrington who the Packers are counting on to be an every-down rock in the middle of defensive coordinator Dom Capers’ defense.

A year ago at this time, the 6-foot-1, 240-pound inside linebacker had barely played any defensive snaps at all, but he slowly absorbed more responsibility as the 2014 season progressed. By the NFC title game in January, Barrington was playing all three downs.

Although Barrington's extremely young at the position, the Packers likely will be asking even more of the former seventh-round pick this season. Never mind that he has all of seven career starts.

“It’s crazy because not until you said it do I really think about it,” Barrington said. “You keep saying, ‘Young guys. Young guys.’ I haven’t been in the league that long. It’s cool because I take my work so serious that the small things I’m able to pass along to the guys younger than me.”

Barrington was the lone bright spot for what was otherwise a lost season for the inside linebackers. Coincidentally, his first start came after he’d sat out two weeks with a hamstring injury. He assumed the role permanently after a five-tackle performance against New England in Week 13.

The Packers made significant changes to the position this offseason in releasing Hawk and Jones, and not re-signing Lattimore. Instead of bringing in a veteran, the Packers converted Palmer and Bradford from outside linebackers and drafted Ryan in the fourth round.

Barrington has rotated next to all three of them with the first-team defense when he’s not working next to Matthews, whose midseason move inside has been credited for saving the defense’s season. Statistically, the run defense halved its yards allowed in the second half of the season after the switch.

Barrington’s maturation also can be linked to the turnaround. With the return of nose tackle B.J. Raji from biceps surgery, the Packers are feeling better about the middle of their defense.

“I really do. I won’t say it specifically because of those guys,” said Barrington of Matthews and Raji. “I just think we all have a certain mentality that I think we can all just do well if everybody’s on the field having the same mentality, I think we’ll do well. It’s like an understanding.”

Barrington’s hard-hitting style translated to 53 tackles and a sack in 14 games last season. It also instilled enough confidence in Capers to allow Barrington to relay the defensive calls late in the season, duties he previously handled during his time at the University of South Florida.

Barrington says his communication still isn’t “flawless.” There are times when he needs to turn up the volume, but appreciates having a core of veteran players around him who are willing to listen and help when the time calls for it.

One of those veterans is fourth-year defensive lineman Mike Daniels, who lauded Barrington last season for the energy he added to the defense. Even when he wasn’t playing, it was one of the first things coaches noticed after Barrington arrived in Green Bay.

“I think it was always in Sam,” assistant linebackers coach Scott McCurley said. “It may have just been the opportunity presented itself and he took off with it. He’s a great competitor. He loves the challenge out there. When you talk about the personality of a football player, he loves the game.

“The more confidence, the better he played and the more he grew.”

Barrington admits things felt different coming into his third training camp. His mentality hasn’t changed, but the expectations certainly have. He’s no longer a late-round draft pick trying to make the 53-man roster. Now, Barrington is looked on to fill a significant role.

Have things slowed down for Barrington? To an extent, but there’s still plenty to learn. Barrington uses 17-year NFL veteran Ray Lewis as an example of an inside linebacker who constantly reinvented himself and adapted his game accordingly.

“I’m still trying to get to that point,” Barrington said. “I’m still trying to get to that point and I’m embracing the journey. I’m taking value of everything I learn in the journey. I’m not to that point where I’m saying, ‘Man, things are still trying to slow down.’

“I hope it never slows down for me. I want to keep learning stuff and playing on the fly, in a sense.”

For young inside linebackers looking to make an impact, McCurley feels there’s no better example than Barrington of the opportunity available to those willing to seize it. Barrington played strictly special teams his rookie season and finished the year on injured reserve with a hamstring injury.

After he returned, Barrington had to claw his way up a cluttered depth chart. When his turn came, he made the most of it. The Packers are counting on another unsung contributor to come out of the defensive woodwork, whether it’s Ryan, Palmer, Bradford or even undrafted free agent Joe Thomas.

“There’s no question Sam sees himself as a leader and the rest of his teammates ... trust him that way,” McCurley said. “Just because of the way he plays garners him a lot of respect from his teammates. He plays hard. He plays aggressive.”

Barrington laughs when he’s asked about all the young guys he’s working with. He gives a reminder that he’s still a young guy, too. For the Packers to be as versatile as they want to be with Matthews, they’ll need the third-year inside linebacker to play beyond his years.

Barrington’s locker was in arm’s reach of Hawk’s the past two seasons. He constantly picked the veteran’s brain about the nuances of the defense and his position. On Monday, it was Barrington who was the veteran moving young guys around on the practice field and showing them how things are done.

It’s a role he feels comfortable with.

“I think that’s just life at its finest,” Barrington said. “You find yourself in a certain situation and then next thing you know you open your eyes and it’s changing. You really just have to adapt and be the type of person who takes whatever comes to you. So I’m adapting.”